Sound directing or amplifying horn and like acoustic apparatus



June 22 1926.

E. A. GRAHAM SOUND DIRECTING 0R AMPLIFYING HORN AND LIKE ACOUSTIC APPARATUS Filed Sept. 17 1925 2 Sheets-Sheet 1 \3 59M W W XYWFM w ii June 22 1926. 1,589,880

E. A. GRAHAM SOUND DIRECTING OR AMPLIFYING HORN AND LIKE ACOUSTIC APPARATUS Filed Sept. 17 1923 2 Sheets-Sheet 2 Patented June 22, 1926.

ED'WARD ALFRED GRAHAM, 0F BROCILEY, LONDON, ENGLAND.

BOUND DIRECT-1N6 0B AMPLIFYING HORN AND LIKE ACOUSTIC APPARATUS.

Application filed September 17, 1923, SeriaiNo. 663,300, and in Great Britain March 27, 1923.

The conical or other shaped horns, sound one from the other in a longitudinal direction conduits, trumpets or the like (hereinafter referred to as horns) commonly used with loud speaking telephonic receivers and grainophones for directing and amplifying the sound produced b the diaphragms or equivalent of such 'te'ephonic receivers or gramophones, impartto the amplified sound waves, secondary superimposed or additional waves which intcrfer with the primary sound waves to such an extent as to produce distortion of wave form and consequent change in character, resulting in loss of definition in the amplified sound. lVith a view to avoiding, reducing or controlling this effect, which is commonly known as trumpet resonance, horns have been made of various substances that are of such mass or character as to be without, or substantially so, a natural vibratory period. Also, it has been proposed to construct horns in several longitudinal sections for the purpose of portability, and also to construct horns in parts and connect such parts by elastic material. Such horn constructions however possess various disadvantages and also do not enable such good results to be obtained as is desirable.

The present invention has for its object so to construct sound directing or amplify ing horns for the emission of sound, as originated by vibrating diaphragms or equivalents, as in loud speaking telephone receivers or gramophones, as better to preserve the tonal qualities of the original sound than the horns heretofore used.

Also, it has for, its object, in the case of horns or sound conduits terminating in a trumpet flare, to enable such flare to be readily detached from the remainder of the horn or sound conduit to facilitate storing or transport, and to be readily replaced for use.

For this purpose a horn is made in two or more longitudinal sections fitted one into the other, plug and socket fashion, and acoustically insulated one from the other by an interposed tubular cushion or bush of sound insulating material of substantial thickness or section, held in a compressed condition. The socket section intended to receive the plug section is preferably formed with a surface which in cross section is curved complementary to a like curved surface upon the sound insulating bush so that after the bush is inserted in the socket, separation of is effectually resisted. The interposed tubular cushion or bush may be formed of indiarubber, fabricated or natural cork, closely woven felt, or other suitable sound insulating, sound-absorbing or non-sonorous material. In certain modifications the bush may be formed of pure soft lead or copper either in a massive or fibrous form. The sections of the trumpet and interposed tubular cushions are connected or anchored together in such a manner that no rigid portion of one section is in actual mechanical contact with a rigid portion of another section and so that the sections, or some of them, can readily be disconnected from one another.

In the accompanying illustrative drawings, Fig. 1 shows in longitudinal section and Fig. 2 in cross section on the line IIII of Fig. 1, one construction of horn according to the invention. Fig. 3 shows in longitudinal section, the jointed end portions of two sections of a further modified constructicn of horn. Fig. 4 shows in end View and Fig. 5 in side view, the sound insulating bush shown in Fig. 3. Figs. 6 and 7 are cross sections of the bush, corresponding to the lines VI-VI and VIIVII respective- ]y of Fig. 4. Fig. 8 is a sectional detail view showing a modification.

In the example shown in Figs. 1 and 2, the horn comprises two sections, namely a section a of bent shape and of gradually increasing cross sectional area from its smaller end, designed for connection to a telephone receiver or Sound box of a gramophone, and a terminal section I) of spreading, conical or trumpet shape adapted for the dispersal of sound waves, the adjacent ends a and b of the two sections being formed the one as a socket and the other as a plug so that they can be inserted one in theother. d is a bush of suitable sound insulating material of the kind referred to, conveniently of soft rubber, inserted between and held in compression by the socket and plug portions a and b of the two sections a and b. The juxtaposed parts are, in this example, connected together by bolts 6, of which conveniently there may be three, each of which extends through the plug portion Z1 of the terminal section 7), the bush d and the socket portion a of the section a and through a boss d of sound insulating material that may, as shown, advantageously be made integral with the bush 0? and serves to prevent contact between the bolt and the socket (4 The bolts are fitted with washers e and nuts 6 so that the parts can be firmly connected together in a readily disconnectable manner. The smaller end of the section a is also formed with a socket a for the reception, as shown in dotted lines in Fig. 1, of a tubular nozzle f on a telephone receiver 7, or gramophone sound box, a bush 9 of sound insulating material for instance soft rubber, being held between the socket and nozzle, as described in the specification of my British Letters Patent No. 191,801.

The horn instead of being made of the bent shape shown, may be of other bent shape, or it may be straight if desired,

By the construction described, sound waves set up by the vibrating diaphragm or equivalent or" the telephonic receiver or the like will proceed through the sections a and b of the horn, expanding during thei r travel, but the pressure exerted by the insulating bushes d and 9 will prevent prejudicial vibrations being set up in the sections, or of any minor vibrations set up in the inner section a being communicated to the outer section b and thence to the ex ternal air. Consequently, the sound waves originally produced, are expanded and dis persed with their original characteristics preserved.

Each of the sections of the horn may be of metal, as in the example shown in Figs, 1 and 2, but they may be of other material, for example wood. Or the inner sec tion or sections may be of metal and the outer terminal or flaring section be of wood. In this case the latter section may be built up of longitudinal sections of wood held together by longitudinal strips oi wood or metal, the end portions of which at the smaller end or plug portions of the section take into longitudinal grooves in the bush of sound insulating material inter posed between said plugportion and the adjacent socket portion of the adjacent section of the horn, which may be of metal.

Figs. 3 to 7 show an arrangement of this kind wherein the section a is of metal and the terminal or flaring section is built up of longitudinal sections 6 of wood held together by longitudinal connecting pieces b of wood of oval section and into opposite longitudinal grooves in which the pieces F)? are fitted. The bush 0? of sound insulating material, is shaped externally to lit the socket a of the section a and is formed internally with longitudinal ribs (Z and intervening grooves cl adapted respectively to lit the longitudinal sections 79 and connecting pieces 6 of the flaring section of the horn. The two sections and interposed bush are connected together by bolts 6 extending through the sections 6 bush (Z and bosses a and fixed in place by nuts 6 as in the other example hereinbetore described.

If desired and as shown in Fig. 8, a washer e and a bush (Z of sound insulating material may be inserted between the head 6 and adjacent shank portion of each bolt and the adjacent part of the flaring or other section of the horn against which the head bears.

hat I claim is:

1. A sound directing or amplifying horn, a joint comprising a section formed with a socket the entrance to which is contracted in relation to a region intermediate of such entrance and the bottom of the socket, a bush of sound insulating material having an external surface complementary to that of the socket so that movement oi the bush in a longitudinal direction, after insertion therein, is resisted, a second horn section having a spigot end adapted to lit plugwise in the bush aforesaid and means for connecting said sections and bush together.

2. A sound directing or amplifying horn, a joint comprising a section formed with a socket the entrance to which is contracted in relation to a region intermediate of such entrance and the bottom of the socket and having holes in such intermediate region, a bush of sound insulating material having an external surface complementary to that of the socket so that movement oi the bush in a longitudinal direction after insertion therein, is resisted, and further provided with integral tabular bosses adapted to extend tl'irough the holes in the socket aforesaid, a second horn section having a spigot end adapted to tit plug-wise in the bush aforesaid, bolts extending through the sections, bush and bosses of the latter and nuts upon the bolts arranged to clamp the said parts together.

Signed at Crofton Park, London, England, this siXth day of September,

EDl/VARD ALFRED GRAHAM. 

